What do the self-tests of the ASM330LHH actually prove?

[FedIng]

Hello, I hope you are well.

I had a query about the IMU ASM330LHH. I want to know whether the self-test functions of the internal accelerometer and gyroscope (see attached pictures) test the internal MEMS sensors or not. I have doubts whether these self-tests only internally generate standard values for acceleration and angular velocity without actually testing the MEMS.

Thank you very much.

[Issamos · Accepted solution]

Hello @FedIng 

The embedded self-test functions allow checking the device functionality without moving it.

Also, When the accelerometer self-test is enabled, an actuation force is applied to the sensor, simulating a definite input acceleration. In this case, the sensor outputs exhibit a change in their DC levels which are related to the selected full scale through the sensitivity value.

The accelerometer self-test function is off when the ST[1:0]_XL bits of the CTRL5_C register are programmed to 00. It is enabled when the ST[1:0]_XL bits are set to 01 (positive sign self-test) or 10 (negative sign self-test). When the accelerometer self-test is activated, the sensor output level is given by the algebraic sum of the signals produced by the acceleration acting on the sensor and by the electrostatic test-force.

For more informations about the self-test, take a look at the chapter 9 of the AN5296.

Best regards.

II

[FedIng]

¡Thank you so much @Issamos for the complete answer and the AN link!